Device for clamping and advancing elongated workpieces

ABSTRACT

For the advancing or feeding motion of bars, wires or the like up to now in most cases two hydraulic devices were used, one for gripping the rod and the other for moving it. According to the invention, to make the apparatus more simple, one single hydraulic cylinder is used for this purpose and according to one embodiment of the invention the piston moved in the hydraulic cylinder actuates at the beginning of its stroke the gripping means and thereafter it shifts this gripping means together with the rod or other workpiece; according to another embodiment the piston is used only for the moving or feeding but the gripping is produced by a series of rings actuated by the same hydraulic fluid which acts on the said piston.

PAIENTEBFms m2 I 3,642 1 86 sum 1 or 2 Fig.2

INVENTORS 4/6265; NFMETH ERA J (soy/13 BY r ATTORNEYS PATENTEBFEB 15 m:3.642. 1 86 saw 2 0F 2 Fig.4

INVENTORS BY r @M ATTOR NEY5 DEVICE FOR CLAMPING AND ADVANCING ELONGATEDWORKPIECES The invention relates to a device for clamping and advancingunder pressure elongated workpieces such as rods, bars, wires and stripsduring continuous production, especially for feeding cutting off,blanking and piercing equipment.

The hitherto known clamping or griping devices do not make possible thegrasping of workpieces along a great surface, that is to say with alarge force and still with a low specific pressure. The inventionsecures the solution of this problem with simple means and maintainingat the same time quick operation.

The present invention relates primarily to a clamping device for bars,the essential character of which consists in a series of segmented ringsenclosing the workpiece (bar, wire etc.), the rings being encircled byan elastic cylindrical membrane, which membrane is pressing under theaction of a compression medium the segmented rings onto the workpiece.If the action of the compression medium is interrupted, the clamping(gripping) action ceases as well. This method of clamping has the greatadvantage against the hitherto known clamping constructions that thegripping is distributed to several ring segments which can be movedindependently from each other and so the total compressing force isacting on a great surface even in that case if there are distortions onthe surface of the workpiece due to the processing or some other faults.The structure and the operation of the device is in spite ofthe greatnumber of the rings very simple and the efficiency is good, because therings are actuated by a common, elastic cylindrical membrane.

The currently applied feeding or advancing systems include two separatehydraulic or pneumatic cylinders, which are ac tuated at least by twopneumatic or hydraulic valves. The expenditures connected with theassembling and the control of such cylinders and the valves increaseconsiderably the costs of such equipments. The equipments set up fromtwo cylinders are not only intricate, but are inherited with thedeficiency that after each rod or workpiece there remains sometrimmings, or the end of the workpiece must be processed by manualfeeding.

The invention aims the elimination of the disadvantages of the saidequipments with similar destination, by establishing a method, accordingto which the clamping and advancing of the starting material is effectedby a special piston system, located within one single cylinder; theseequipments can be set up according to the requirements, have smalldimensions and at the same time great output, are according to the setupof single or double action, and besides of this are able to transfervery great axial forces through the help of any suitable high-pressuremedium used for energy transfer. With the help of this equipment it ispossible to produce axial stresses of such an order of magnitude in theadvanced material (rod, bar or the like), which is sufficient to effectflow of the material (especially in the vicinity of the end ofthe rod).

The abutting of the equipment can be effected rigidly or elastically.The feeding length can be adjusted easily and quickly, besides of thisthe manufacturing costs of the equipment are low when compared with thecosts of other equipments with similar destination.

A more detailed exposition of the method and device according to theinvention is described in connection with the embodiments given by wayof example and shown in the enclosed figures.

FIGS. 1 and 2 are showing a possible embodiment of the device, suitableto carry out the method according to the invention. FIG. 1 shows alongitudinal section of the device, whereas FIG. 2 illustrates anothersection along the plane A of FIG. I in clamping position.

The clamping-advancing device is situated in a cylinder 7 which isclosed on both ends by heads 11 and 12. The gripping of the workpiece 8is effected by bellcrank levers 2, which are connected through pins 4acting as hinges to a slotted disc 3, which is sliding in the cylinder 7with tight running fit. The

levers 2 are connected with the actuating piston I through a tilting pin13. The workpiece 8 and the actuating space of the cylinder areseparated by a sleeve 14, which is tightly fitted on his left end to thepiston l.

The device is returned to the starting piston by a spring 6. The pistonl is actuated by the spring 6 through a spring retained 9 by the help ofshouldered pins 5.

The operation of the device is as follows: through the effect of theactuating medium which is let in through a slot 10 of the head 12 seenin FIG. 1, the piston l is moved in the cylinder 7 together with thesleeve 14 to the left and since there arises a relatively great frictionforce between the slotted disc 3 and the cylinder 7, the effect turnsthe bellcrank levers 2 around the pins 4. The proportion of the arms ofthe levers 2 is selected in such a way that one arm of each lever isforced as a consequence of the turning to the workpiece 8 and aregripping the same. Simultaneously with the clamping of the workpiece 8the shouldered pin 5 which is screwed to the piston l is also moving tothe left, acting with its shoulder on the spring retainer 9 andcompressing the spring 6.

During the first phase of the operation the workpiece 8 due to thegripping of the clamping arms and the pressure of the spring 6, as wellas the travelling parts 1, 2, 3 and 9 within the cylinder 7 are forminga unique system moving together.

If further actuating medium is streaming in, the travelling parts aremoved further to the left compressing at the same time the spring 6 andtaking along the workpiece 8. This motion is continued until the leftend of the workpiece 8 is abutting (on a not shown stop).

After the cessation of the pressure of the actuating medium the spring 6is moving the spring retainer 9 and the actuation piston l to the right,with the help of the shouldered pins 5. As a consequence of thismovement the tilting pins 13 are turning the clamping arms 2 and therebyreleasing the gripping of the workpiece 8. Due to the fact that at firstthe shouldered pin 5 is setting in movement the piston 1 and the otherparts while the disc 3 is still stationary, the workpiece is releasedand the other parts of the device are travelling only thereafter. Thissecures that during the resetting of the device the workpiece is notmoved. During resetting the spring retained 9 is moved by the spring 6against the slotted disc 3 and the travelling parts 1, 2, 3 and 9 arereturned to their original position to the right.

FIGS. 3 and 4 show the longitudinal and the cross section respectivelyof another possible form of the device, suitable to carry out the methodaccording to the invention. This embodi ment can be applied especiallywell to cutting off and cold-extrusion machines with smaller or greatercapacity. It is suitable to transfer or hold even in the case of rods,bar and profiles with greater cross section such axial forces, which aresetting up stresses in the bars surpassing the yield strength.

From the above explanation it is clear that the gripping of theworkpiece and its feeding too is effected by one single piston, so thataccording to the invention only one cylinder 7 is necessary.

The clamping-advancing device seen in FIGS. 3 and 4 in longitudinal andin cross section is situated in a fixed cylinder 15 and is divided intothree actuating spaces.

The radial gripping space 1 is delimited by an elastic sealing sleeve 18and a distance ring 25. The segmented power trans mission rings 17 andclamping rings 16 are situated within the elastic sealing sleeve 18. Theclamping rings 16 and the power transmission rings 17 are manufacturedin two or more segments. In FIG. 4 a form of these rings can be seen byway of example. In order to secure the relative position of thedivisions in the same axial plane, key 21 is inhibiting the rotation ofthe rings relative to each other, while an elastic insert 19 is movingoff the two half-rings from each other. The gripping elements mentionedabove are delimited on both sides by heads 26 and 27 screwed to thedistance ring 25 The advancing and axial power transferring space II isdelimited by the piston 20 within the cylinder 15, the head 22 and thesleeve 31, while a retracting space III is delimited by the ring 24fitted to the cylinder I5, the piston 20 and the power-transferring ring23 screwed to the head 27 and the piston 20.

The operation of the device is as follows: high-pressure oil is ledthrough the admitting ports 28 and 29 simultaneously to the actuatingspaces l and ll. The oil led through the admitting port 28 is acting onthe elastic sealing sleeve 18, compressing the elastic insert 19 andmoving the power transmission rings 17 and clamping rings 16 towardseach other, gripping hereby the workpiece 8.

Following this, the oil led through the admitting port 29 is acting onthe right surface of piston and hereby forcing the same to the left,together with the power-transferring ring 23 as well as the connectedclamping system consisting of the parts 27, l6, l7, 18, and 26, with thealready gripped workpiece 8. This leftward movement is continued untilthe left end of workpiece 8 is abutting. This state conforms to theworking position of the device.

After the time period necessary for the work cycle has passed, theoverpressure is ceased in the working spaces I and ll, clue to which theclamping rings 16 are releasing under the action of the elastic insert19 the workpiece 8. After having annulled the overpressure in theworking spaces 1 and ll, oil is led through the admitting port into theretracting space Ill. The inflowing oil is acting on the left ringsurface of the piston 20 and hereby forcing the same to the right,together with the power-transferring ring 23 as well as the clampingsystem consisting of the parts 27, 16, 17, 18, 25 and 26, up to therighthand terminal position.

Due to the elasticity of the membrane each clamping ring segment iseffecting during gripping the required clamping force, even in that caseif there are irregularities or defects on the surface ofthe workpiece.

We claim:

1. In a fluid pressure device for clamping and advancing an elongatedworkpiece, comprising a stationary cylinder, a piston in the cylindersubjected to the action of a fluid pressure medium, said piston havingan interior space through which the workpiece advances and which isisolated from said fluid pressure medium, a plurality of bellcranklevers engageable with the workpiece on the side of the piston oppositesaid medium, one arm of each said lever contacting said piston and theother arm contacting the workpiece, a slotted disc in which the rotatingpivots of the levers are disposed, said disc being disposed in thecylinder; the improvement comprising a plurality of shouldered pins (5)with a spring retainer (9) urged by a spring (6) in a direction oppositethat in which the fluid pressure medium urges the piston so that thepins attached to the piston are supported on the spring retainer bytheir shoulders and extend through said slotted disc (3).

2. In a fluid pressure device for clamping and advancing an elongatedworkpiece a stationary cylinder, a series of segmented rings encirclingand clamping the workpiece, an elastic cylindrical membrane enclosingthe series of segmented rings and disposed in a ringlike fluid pressurespace in such a way that said membrane delimits said space on one side,said stationary cylinder delimiting said space on the opposite side,said space communicating with a source of fluid pressure medium; theimprovement comprising a further series of segmented power-transferringrings (17) outside the first-mentioned series (16) clamping theworkpiece, elastic inserts (1?) in the division plane of some of saidrings, and keys (21) contacting the rings and inhibiting their turning.

3. A device as claimed in claim 2, there being three spaces in saidcylinder (15), one of said spaces (l) being delimited by saidcylindrical membrane (18), the other two (ll) and (Ill) of said spacesbeing disposed on opposite sides of a piston (20) that moves theworkpiece and the clamping rings.

4. A device as claimed in claim 3, and two heads (26 and 27) secured toa distance ring (25) disposed within said one space (I), said headsconfining between them said rings and being slidably disposed in saidstationary cylinder (15), one of the heads (27) being securedto saidpiston (20).

5. In a fluid pressure device for clamping and advancing an elongatedworkpiece, a piston (1) subjected to the action of the actuating mediumand situated in a fluid pressure cylinder (7), at least two bellcranklevers (2) forced against the workpiece, one arm of said leverscontacting said piston and the other arm of the same contacting theworkpiece, the rotating pivots (4) of these levers being arranged in aslotted disc (3) fitted in the cylinder, the actuating piston beingconnected through at least two shouldered pins (5) with a springretainer (9) working under the action of a spring in such a way that thepins (5) attached to the piston (1) are supported on the spring retainer(9) by their shoulders and are led through the slotted disc (3) holdingthe bellcrank levers (2).

6. In a fluid pressure device for clamping and advancing an elongatedworkpiece, a series of segmented rings (16) encircling and clamping theworkpiece and an elastic cylindrical membrane (18) enclosing said seriesof segmented rings, which is situated in a ringlike fluid pressure space(I) in such a way that it delimits this space on one side, whereas thespace is delimited on the other side by a stationary cylinder (25) andthe said space communicates with a source of fluid pressure, a furtherseries of segmented power-transferring rings (17) outside the series ofsegmented rings (16) clamping the workpiece, elastic inserts (19) in thedivision plane of the powertransferring rings, and keys (21) contactingsaid rings and inhibiting their turning,

7. A device according to claim 6, characterized by three spaces in thestationary pneumatic or hydraulic cylinder (15), from which one (I) isdelimited by said cylindrical membrane (18), whereas the other two (IIand lll) are situated on both sides of a piston (20) which moves theworkpiece and the clamping device.

8. A device according to claim 7, characterized by two heads (26 and 27)attached to the distance ring (25) situated within the fluid pressurespace (I) of the series of segmented rings (16), said heads confiningsaid rings between them, these heads being slidably disposed in thestationary cylinder (15), one of the heads (27) being attached to theactuating piston (20).

1. In a fluid pressure device for clamping and advancing an elongatedworkpiece, comprising a stationary cylinder, a piston in the cylindersubjected to the action of a fluid pressure medium, said piston havingan interior space through which the workpiece advances and which isisolated from said fluid pressure medium, a plurality of bellcranklevers engageable with the workpiece on the side of the piston oppositesaid medium, one aRm of each said lever contacting said piston and theother arm contacting the workpiece, a slotted disc in which the rotatingpivots of the levers are disposed, said disc being disposed in thecylinder; the improvement comprising a plurality of shouldered pins (5)with a spring retainer (9) urged by a spring (6) in a direction oppositethat in which the fluid pressure medium urges the piston so that thepins attached to the piston are supported on the spring retainer bytheir shoulders and extend through said slotted disc (3).
 2. In a fluidpressure device for clamping and advancing an elongated workpiece astationary cylinder, a series of segmented rings encircling and clampingthe workpiece, an elastic cylindrical membrane enclosing the series ofsegmented rings and disposed in a ringlike fluid pressure space in sucha way that said membrane delimits said space on one side, saidstationary cylinder delimiting said space on the opposite side, saidspace communicating with a source of fluid pressure medium; theimprovement comprising a further series of segmented power-transferringrings (17) outside the first-mentioned series (16) clamping theworkpiece, elastic inserts (19) in the division plane of some of saidrings, and keys (21) contacting the rings and inhibiting their turning.3. A device as claimed in claim 2, there being three spaces in saidcylinder (15), one of said spaces (I) being delimited by saidcylindrical membrane (18), the other two (II) and (III) of said spacesbeing disposed on opposite sides of a piston (20) that moves theworkpiece and the clamping rings.
 4. A device as claimed in claim 3, andtwo heads (26 and 27) secured to a distance ring (25) disposed withinsaid one space (I), said heads confining between them said rings andbeing slidably disposed in said stationary cylinder (15), one of theheads (27) being secured to said piston (20).
 5. In a fluid pressuredevice for clamping and advancing an elongated workpiece, a piston (1)subjected to the action of the actuating medium and situated in a fluidpressure cylinder (7), at least two bellcrank levers (2) forced againstthe workpiece, one arm of said levers contacting said piston and theother arm of the same contacting the workpiece, the rotating pivots (4)of these levers being arranged in a slotted disc (3) fitted in thecylinder, the actuating piston being connected through at least twoshouldered pins (5) with a spring retainer (9) working under the actionof a spring in such a way that the pins (5) attached to the piston (1)are supported on the spring retainer (9) by their shoulders and are ledthrough the slotted disc (3) holding the bellcrank levers (2).
 6. In afluid pressure device for clamping and advancing an elongated workpiece,a series of segmented rings (16) encircling and clamping the workpieceand an elastic cylindrical membrane (18) enclosing said series ofsegmented rings, which is situated in a ringlike fluid pressure space(I) in such a way that it delimits this space on one side, whereas thespace is delimited on the other side by a stationary cylinder (25) andthe said space communicates with a source of fluid pressure, a furtherseries of segmented power-transferring rings (17) outside the series ofsegmented rings (16) clamping the workpiece, elastic inserts (19) in thedivision plane of the power-transferring rings, and keys (21) contactingsaid rings and inhibiting their turning.
 7. A device according to claim6, characterized by three spaces in the stationary pneumatic orhydraulic cylinder (15), from which one (I) is delimited by saidcylindrical membrane (18), whereas the other two (II and III) aresituated on both sides of a piston (20) which moves the workpiece andthe clamping device.
 8. A device according to claim 7, characterized bytwo heads (26 and 27) attached to the distance ring (25) situated withinthe fluid pressure space (I) of the series of segmented rings (16), saidheads confining said rings between them, these heads Being slidablydisposed in the stationary cylinder (15), one of the heads (27) beingattached to the actuating piston (20).